Surface-mounted oscillator

ABSTRACT

A surface-mounted oscillator configured by integrally accommodating an oscillation element, an IC chip, and a circuit element in a surface-mounted package is characterized in that the oscillation element, the IC chip, and the circuit element are arranged in positions in a direction vertical to a mounting surface of the surface-mounted oscillator. The oscillation element may be an oscillation element using bulk wave oscillation, or an oscillation element using surface wave oscillation.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a surface-mounted oscillator, and moreparticularly, to a technique for reducing the planar dimensions of thesurface-mounted oscillator.

2. Description of the Related Art

Since a surface-mounted oscillator is small-sized and lightweight, itis, for example, included in a portable appliance, and widely used as afrequency or time reference source, etc. For example, if a portableappliance to be used is a telephone, a temperature compensatedoscillator (TCXO) disclosed by Patent Document 1 is used because of itsdynamic environments.

A surface-mounted oscillator is configured to accommodate, in asurface-mounted package, an oscillation element such as a crystal piece,etc., an IC (Integrated Circuit) chip in which an oscillation circuit, atemperature compensation circuit, etc., are integrated, and a circuitelement composed as a discrete component such as a capacitor, etc.,which cannot be integrated within the IC chip.

FIGS. 1 to 3 are cross-sectional views showing the internalconfigurations of normal surface-mounted oscillators.

FIG. 1 shows a surface-mounted oscillator recited in Patent Document 2.In this oscillator, an oscillation element 1, an IC chip 2, and acircuit element 3 composed as a discrete component such as a capacitor,etc. are integrally accommodated in a surface-mounted package 4 of aso-called H structure type.

The surface-mounted package 4 is configured by comprising concaveportions on both of its main surfaces, and by integrating an oscillationelement 1, which is sealed with a cover 9 after being accommodated inthe concave portion on one of the main surfaces, and the IC chip 2 andthe circuit element 3, which are accommodated in the other concaveportion.

FIG. 2 shows a surface-mounted oscillator recited in Patent Document 3.The surface-mounted oscillator shown in this figure has a configurationof a junction type, where a surface-mounted package 4 is separated intoa package 5 and a mounting board 6, and the concave mounting board 6 inwhich an IC chip 2 and a circuit element 3 are accommodated is joined tothe bottom of a crystal oscillator configured by hermetically sealing anoscillation element 1 with a cover after accommodating the oscillationelement 1 in the package 5.

FIG. 3 shows a surface-mounted oscillator recited in Patent Document 4.The surface-mounted oscillator shown in this figure has a configurationof a single space type, where an IC chip 2, a circuit element 3, and anoscillation element 1 are hermetically sealed with a cover 9 in the samespace after the IC chip 2 and the circuit element 3, and one end of theoscillation element 1 are respectively secured to the bottom of aconcave portion of a surface-mounted package 4, and to a stage portionon an inner wall of the concave portion in the surface-mounted package4.

[Patent Document 1]

Japanese Patent Publication No. 2000-244243

[Patent Document 2]

Japanese Patent Publication No. HEI8-204452

[Patent Document 3]

Japanese Patent Publication No. 2003-179433

[Patent Document 4]

Japanese Patent Publication No. HEI9-298440

Currently, the planar dimensions of a surface-mounted oscillator are,for example, on the order of 3.2 by 2.5 mm, but there is a demand forfurther reducing the dimensions. Additionally, as an oscillationfrequency increases, the size of an oscillation element 1 such as acrystal piece, etc. becomes smaller. However, there is a problem that anincrease in planar dimensions cannot be avoided, because an IC chip, anda discrete component such as a capacitor, etc. are arranged on the sameflat surface.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a surface-mountedoscillator, the planar dimensions of which can be reduced, and whichaccommodates an oscillation element, an IC chip, and a circuit element(discrete component).

The present invention assumes a surface-mounted oscillator configured byintegrally accommodating an oscillation element, an IC chip, and acircuit element in a surface-mounted package, and is characterized inthat the oscillation element, the IC chip, and the circuit element arearranged in positions in a direction vertical to a mounting surface ofthe surface-mounted oscillator.

The surface-mounted package may be configured to comprise a firstconcave portion that accommodates the oscillation element on a firstmain surface, and a second concave portion that accommodates the IC chipand the circuit element on a second main surface as opposed to the firstmain surface.

Or, the surface-mounted package may be configured by joining a firstpackage that accommodates the oscillation element, and a second packagethat accommodates the IC chip and the circuit element.

Or, the surface-mounted package maybe configured to comprise a concaveportion that accommodates the oscillation element, the IC chip, and thecircuit element.

Or, the oscillation element may be an oscillation element using bulkwave oscillation, which entirely oscillates, or an oscillation elementusing surface wave oscillation, only the surface of which oscillates.

According to the present invention, the oscillation element, the ICchip, and the circuit element are arranged in positions in a verticaldirection, whereby the planar dimensions of the surface-mountedoscillator can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view showing a first example of aconventional surface-mounted oscillator;

FIG. 2 is a cross-sectional view showing a second example of aconventional surface-mounted oscillator;

FIG. 3 is a cross-sectional view showing a third example of aconventional surface-mounted oscillator;

FIG. 4A is a conceptual schematic showing an arrangement of constituentelements in a conventional surface-mounted oscillator;

FIGS. 4B and 4C are conceptual schematics respectively showing anarrangement of constituent elements in a surface-mounted oscillatoraccording to the present invention;

FIG. 5A is a cross-sectional view showing a surface-mounted oscillatoraccording to a first preferred embodiment;

FIG. 5B shows its bottom view;

FIGS. 6A, 6B, 6C, and 6D are cross-sectional views respectively showinga surface-mounted oscillator according to a second preferred embodiment;

FIGS. 7A, 7B, and 7C are cross-sectional views respectively showing asurface-mounted oscillator according to a third preferred embodiment;

FIG. 8 is a schematic exemplifying a case where the surface-mountedoscillator comprises a plurality of circuit elements composed ofdiscrete components; and

FIG. 9 is a schematic showing a configuration where a SAW is used as anoscillation element.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Fundamental principle of the present invention is first described.

FIG. 4A is a conceptual schematic showing the arrangement of constituentelements in the conventional surface-mounted oscillators shown in FIGS.1 to 3.

In the conventional surface-mounted oscillators, an IC chip 12, and acircuit element 13 composed of a discrete component such as a capacitor,etc. are accommodated by being arranged in a package 10 a in a directionhorizontal to a mounting surface 14 a comprising mounting electrodes notshown.

With an increase in output frequency demanded for a surface-mountedoscillator in recent years, the size of an oscillation element 11 hasbeen decreasing. Additionally, in a temperature compensated oscillator,etc., an IC chip 12 also includes a temperature compensation circuit,etc. Therefore, its size is approximately the same as that of anoscillation element 11 composed of a crystal piece. Accordingly, theplanar dimensions of a conventional surface-mounted oscillator aredetermined by a size obtained by combining areas where the IC chip 12and the circuit element 13 are respectively mounted.

Considering this point, in a surface-mounted oscillator according to thepresent invention, respective constituent elements are arranged inpositions in a vertical direction.

FIGS. 4B and 4C are conceptual schematics respectively showing anarrangement of constituent elements in the surface-mounted oscillatoraccording to the present invention. In FIG. 4B, an oscillation element11, a circuit element 13, and an IC chip 12 are accommodated in apackage 10 b in this order in a direction vertical to a mounting surface14 b. In the meantime, in FIG. 4C, an oscillation element 11, an IC chip12, and a circuit element 13 are accommodated in a package 10 c in ordermore apart from a mounting surface 14 c.

The circuit element 13 is smaller than the oscillation element 11 andthe IC chip 12. Therefore, in the case of the configuration shown inFIG. 4B or 4C, the planar dimensions of the surface-mounted oscillator10 are determined by a larger one of the areas where the oscillationelement 11 and the IC chip 12 are respectively mounted. Accordingly, theplanar dimensions of the oscillator can be reduced in comparison withthe conventional surface-mounted oscillator which is shown in FIG. 4A,and determined by the combined area where the IC chip 12 and the circuitelements 13 are mounted.

A temperature compensated oscillator using a multilayer ceramic packageis exemplified next as a specific configuration example of thesurface-mounted oscillator according to the present invention.

FIG. 5A is a cross-sectional view showing a surface-mounted oscillatoraccording to a first preferred embodiment, whereas FIG. 5B shows itsbottom view. The configuration shown in FIG. 5 corresponds to theconfiguration shown in FIG. 1, where the surface-mounted package of aso-called structure type is used.

The surface-mounted oscillator shown in FIG. 5A and 5B are configured byaccommodating an oscillation element 21 such as a crystal piece, etc.,an IC chip 22, and a circuit element 23 such as a capacitor, etc. in asurface-mounted package 24 a made of multilayer ceramic. In FIG. 5A, thebottom portion is the mounting surface.

The oscillation element 21 is made of a piezoelectric material such as acrystal piece, etc., and has excitation electrodes not shown on both ofmain surfaces. For example, drawn electrodes are extended, for example,to both sides of one end of the oscillation element 21. The IC chip 22is implemented by integrating circuit elements that configure anoscillation circuit having a temperature compensation mechanism notshown. The circuit element 23 is a circuit element that cannot beintegrated within the IC chip 22, such as a capacitor used, for example,to form with a resistor a lowpass filter, which removes noise caused bythe temperature compensation mechanism, a bypass capacitor which makes ahigh-frequency component pass through, an inductor used to widen thevariable width of a frequency in a voltage controlled oscillator (VCO),and the like. Since the capacitor that forms a lowpass filter requires alarge capacity equal to or higher than 1000 pF, it cannot be integratedwithin the IC chip 22. Accordingly, the capacitor is used as a discretecomponent. Also the bypass capacitor between a power source and a groundcannot be integrated within the IC chip 22 due to its large capacity.Therefore, the bypass capacitor is used as a discrete component.

In the configuration shown in FIG. 5, a hole 30 a is further provided inthe central region of a concave portion 26 a that accommodates the ICchip 22 in the surface-mounted package 24 a of a so-called H structuretype having the main surfaces on both of which the concave portions 25 aand 26 a are respectively provided. After the oscillation element 21 issecured to the concave portion 25 a, in which the hole 30 a is notprovided, for example, with a conducting adhesive 27, it is hermeticallysealed by seam-welding a cover 29. The circuit element 23 is thenaccommodated by being secured to the hole 30 a, which exists in theother concave portion 26 a, with a conducting adhesive or soldering, andthe IC chip 22 is secured to stage portions 31 a of the concave portion26 a with flip chip bonding using bumps 28 to cover the circuit element23. The surface-mounted package 24 a is made of multilayer ceramic, andeach of the concave portions 25 a and 26 a, and the hole 30 a are formedby multilayer ceramic.

With such a configuration, in the surface-mounted oscillator shown inFIG. 5, the oscillation element 21, the IC chip 22, and the circuitelement 23 are three-dimensionally arranged in the vertical direction,whereby the mounting area of the surface-mounted oscillator can bereduced.

Note that opposed two sides of the concave portion 26 a, whichaccommodates the IC chip 22, are made open to increase the mounting areaof the IC chip 22. If the IC chip 22 is small, the concave portion 26 acan be also configured as a concave portion composed of 4 sides withoutmaking the two sides open, as a matter of course.

A second preferred embodiment is described next.

FIGS. 6A, 6B, 6C, and 6D are cross-sectional views respectively showinga surface-mounted oscillator according to a second preferred embodiment.The configurations shown in FIG. 6 correspond to the configuration of ajunction type, which is shown in FIG. 2. In FIG. 6, the fundamentallysame constituent elements as those in the first preferred embodiment aredenoted with the same reference numerals, and their descriptions areomitted or briefly provided.

The surface-mounted oscillator shown in FIG. 6A is configured byseparating a surface-mounted package 24 b into a package 32 in which anoscillation element 21 is sealed, and a mounting board 33 b on which anIC chip 22, and a circuit element 23 such as a capacitor, etc. aremounted. The mounting board 33 is bonded to the bottom of theoscillation element, which is configured by securing the oscillationelement 21 to the package 32, for example, with a conducting adhesive27, and by hermetically sealing the oscillation element 21 with a cover29.

A concave portion 26 b is provided on the mounting board 33 b, and ahole 30 b is provided in the central region of the concave portion 26 b.The circuit element 23 is accommodated in the hole 30 b, and the IC chip22 is secured to stage portions 31 b in the concave portion 26 b withflip chip bonding using bumps 28 to cover the circuit element 23.

Then, the side of the concave portion 26 b of the mounting board 33 band the side of the bottom of the package 32 are joined with soldering.

In the configuration shown in FIG. 6A, the mounting board 33 b may beconfigured upside down. FIG. 6B shows such a configuration.

In this figure, a surface-mounted package 24 c is composed of the samepackage 32 as that in FIG. 6A, and a mounting board 33 c configured byturning the mounting board 33 b upside down, and is configured bybonding the bottom of the package 32 and a surface opposite to a surfacehaving a concave portion 26 c of the mounting board 33 c.

Additionally, FIG. 6C shows a configuration where a mounting board 33 dhaving a concave portion and a hole on different surfaces is bonded tothe bottom of a crystal oscillator configured by the same package 32 asthat in FIG. 6A.

In FIG. 6C, the mounting board 33 d has a concave portion 26 d, whichaccommodates the IC chip 22, on one of two opposed main surfaces, andalso has a hole 30 d, which accommodates a circuit element 23, on theother main surface. The IC chip 22, and the circuit element 23 composedof a discrete component are respectively accommodated in the concaveportion 26 d, and in the hole 30 d, and integrated. Then, the mainsurface having the concave portion 26 d is joined to the bottom of thepackage 32.

Also in the configuration shown in FIG. 6C, the mounting board 33 d maybe configured upside down. FIG. 6D shows such a configuration.

In this figure, a surface-mounted package 24 e is configured by the samepackage 32 as that in FIG. 6A, and a mounting board 33 e implemented byturning the mounting board 33 d upside down, and is also configured byjoining the bottom of the package 32 and a main surface of the mountingboard 33 e, which has a hole 30 e accommodating a circuit element 23.

In the cases of the configurations according to the second preferredembodiment shown in FIG. 6, only the package 32 is examined after theoscillation element 21 is sealed in the package 32, and only a passedpackage can be used to join to the mounting board 33. Accordingly,expensive IC chip 22 and circuit element 23 can be prevented from beingwasted.

A third preferred embodiment is described next.

FIGS. 7A, 7B, and 7C are cross-sectional views respectively showing asurface-mounted oscillator according to a third preferred embodiment.The configurations in FIG. 7 correspond to the configuration of a singlespace type, which is shown in FIG. 3. In FIG. 7, the fundamentally sameconstituent elements as those in the first and the second preferredembodiments shown in FIGS. 5 and 6 are denoted with the same referencenumerals, and their descriptions are omitted or briefly provided.

The configuration according to the third preferred embodiment is aconfiguration where an oscillation element 21 such as a crystal piece,etc., and other constituent elements are sealed in the same space.

In FIG. 7A, in a surface-mounted oscillator, an oscillation element 21such as a crystal piece, etc., an IC chip 22, and a circuit element 23such as a capacitor, etc. are accommodated in a surface-mounted package24 f.

The surface-mounted package 24 f comprises stage portions 34 f, and aconcave portion 26 f on an inner wall. Additionally, a hole 30 f isprovided in the central region of the bottom of the concave portion 26f.

The circuit element 23 such as a capacitor, etc. is accommodated in thehole 30 f, and the IC chip 22 is secured to the stage portions 31 fwithin the concave portion 26 f to cover the circuit element 23.Additionally, after the oscillation element 21 is accommodated to coverthe IC chip 22, for example, by securing one end of the oscillationelement 21 to a stage portion 34 f on the inner wall, it is sealed witha cover 29.

FIGS. 7B and 7C respectively show a modified oscillator of a singlespace type.

In FIG. 7B, only an IC chip 22 is accommodated in a concave portion 26 gprovided in the same space as that accommodating an oscillation element21, and a circuit element 23 is accommodated in a hole 30 g provided onan opposite main surface of a surface-mounted package 24 g. In FIG. 7C,inversely, only a circuit element 23 is accommodated in a hole 30 hprovided in the same space as that accommodating an oscillation element21, and an IC chip 22 is accommodated in a concave portion 26 h providedon an opposite main surface of a surface-mounted package 24 h.

The first to the third preferred embodiments described up to this pointrefer to the cases where only one circuit element 23 such as acapacitor, etc. exists. However, a plurality of circuit elements 23 canbe similarly accommodated also in the case of a configuration where anoscillator uses the plurality of circuit elements 23.

FIG. 8 shows a case where plurality of circuit elements 23 areaccommodated in the surface-mounted oscillator shown in FIG. 5.

Normally, the size of a circuit element 23 is much smaller than anoscillation element 21 and an IC chip 22. Accordingly, as shown in FIG.8, a hole 26 i having a space, in which a plurality of circuit elements23 can be mounted within a mounting area of an oscillation element 21 oran IC chip 22 as shown in FIG. 8, can be provided, and the plurality ofcircuit elements can be accommodated in the hole 26 i.

In this figure, the hole 26 i in which the plurality of circuit elements23 can be mounted is provided in the center of a concave portion 26accommodating the IC chip 22 in the surface-mounted package 24 i, andthe two circuit elements 23-1 and 23-2 are accommodated in this hole 26i. Also in the surface-mounted oscillators having the configurationsaccording to the second and the third preferred embodiments, which areshown in FIGS. 6 and 7, a plurality of circuit elements 23 can beaccommodated.

The above described embodiments refer to the cases where the crystalpiece using bulk wave oscillation is used as the oscillation element 11.However, in the surface-mounted oscillators represented as therespective embodiments, an oscillation element using surface waveoscillation such as a SAW (Surface Acoustic Wave), etc. may be used asthe oscillation element other than the element using bulk waveoscillation.

FIG. 9 shows a configuration where a SAW is used as an oscillationelement in the surface-mounted oscillator shown in FIG. 5.

In this figure, the side of one main surface of an oscillation element35 using a SAW, on which excitation electrodes are formed, is secured tothe bottom of a concave portion of a surface-mounted package 24 j withflip chip bonding using bumps not shown. Similarly, also in thesurface-mounted oscillators having the configurations according to thesecond and the third preferred embodiments, which are shown in FIGS. 6and 7, an oscillation element using surface wave oscillation such as aSAW, etc. can be used as the oscillation element.

At this time, the hermetic of the oscillation element using a SAW, etc.can be low in comparison with the oscillation element using bulk waveoscillation. Therefore, a resin may be available as the surface-mountedpackage 24 j other than multilayer ceramic.

The above provided description refers to the configurations where the ICchip 22 is secured with flip chip bonding. However, the IC chip 22 maybe connected with wire bonding.

Additionally, a resinous agent not shown may be added to protect the ICchip, and the circuit element 23 such as a capacitor, etc. on demand.

In the above described preferred embodiments, the oscillation element21, the IC chip 22, and the circuit element 23 such as a capacitor, etc.are arranged in a vertical direction in all the cases, whereby theplanar dimensions can be held small.

1. A surface-mounted oscillator configured by integrally accommodatingan oscillation element, an IC chip, and a circuit element in asurface-mounted package, wherein the oscillation element, the IC chip,and the circuit element are arranged in positions in a directionvertical to a mounting surface of the surface-mounted oscillator, thesurface-mounted package comprises a first concave portion thataccommodates the oscillation element on a first main surface, and asecond concave portion that accommodates the IC chip and the circuitelement on a second main surface as opposed to the first main surface,and the second concave portion comprises a hole in which the circuitelement is accommodated, and a stage portion to which the IC chip issecured.
 2. A surface-mounted oscillator configured by integrallyaccommodating an oscillation element, an IC chip, and a circuit elementin a surface-mounted package, wherein the oscillation element, the ICchip, and the circuit element are arranged in positions in a directionvertical to a mounting surface of the surface-mounted oscillator, thesurface-mounted package is configured by joining a first package thataccommodates the oscillation element, and a second package thataccommodates the IC chip and the circuit element, and the second packagecomprises a concave portion that accommodates the IC chip, and a holethat accommodates the circuit element in the concave portion.
 3. Asurface-mounted oscillator configured by integrally accommodating anoscillation element, an IC chip, and a circuit element in asurface-mounted package, wherein the oscillation element, the IC chip,and the circuit element are arranged in positions in a directionvertical to a mounting surface of the surface-mounted oscillator, thesurface-mounted package is configured by joining a first package thataccommodates the oscillation element, and a second package thataccommodates the IC chip and the circuit element, and the second packagecomprises a first main surface having a concave portion thataccommodates the IC chip, and a second main surface, as opposed to thefirst main surface, having a hole that accommodates the circuit element.4. A surface-mounted oscillator configured by integrally accommodatingan oscillation element, an IC chip, and a circuit element in asurface-mounted package, wherein the oscillation element, the IC chip,and the circuit element are arranged in positions in a directionvertical to a mounting surface of the surface-mounted oscillator, thesurface-mounted package comprises a concave portion that accommodatesthe oscillation element, the IC chip, and the circuit element, and theconcave portion comprises a hole that accommodates the circuit element.